THE MUSCLES. 



I. THE MUSCLES OF THE SKIN. (Fig. 62.) 



M. cutaneus maximus (Fig. 62, b). — This is a very large, 

 thin muscle which covers almost the whole side of the body. 

 It arises from the outer surface of the latissimus dorsi (Fig. 68, 

 ;;/) near its ventral end and from the bicipital arch (Fig. 65, /') 

 in the axilla; from the Hnea alba for a considerable distance 

 (two or three inches) caudad of the base of the xiphoid process, 

 and from the thorax over a line joining the axilla and the base 

 of the xiphoid. Sometimes a few fibres take origin from the 

 fascia which covers the pectoantibrachialis on the ventral side 

 of the arm. 



From their origin the fibres diverge. The cranial ones 

 curve about the base of the forelimb and are inserted into the 

 skin at or near the middle line caudad of the first thoracic 

 vertebra. The most cranial fibres of all are inserted about one 

 to one and a half centimeters from the middorsal line ; thence 

 the line of insertion approaches the middorsal line to reach it 

 at about the eighth or ninth thoracic vertebra. The middle 

 fibres run parallel to the middorsal line in the lumbar and 

 sacral regions as far as the root of the tail, a small bundle 

 passing onto the dorsal side of the tail, another onto the ventral 

 side. The fibres of the caudal portion pass onto the thigh, the 

 ventral ones running in the fold of skin which stretches from 

 thigh to abdomen, and are finally lost in the fascia along a line 

 connecting the knee and the root of the tail. A strong fascia 

 connects the adjacent borders of the cutaneus and platysma and 

 lies over the scapular region. 



93 



